A vaginectomy--surgical removal of part or all of the vagina--is most often done as part of cancer treatment. It's rarely a doctor's first choice, and some reconstruction is usually involved. Your health care provider's evaluation is an important first step.
If your health care provider believes there's physical capacity for intercourse without further reconstruction, there's more you can do to be sure that you're comfortable. A regular routine with a vaginal moisturizer will help keep your vaginal tissues healthy and elastic. You may want to use a lubricant with penetration. Make sure that you're giving yourself time (and attention!) to become fully aroused. Especially if you're having sex again after some time alone, you may be in a rush!
If you're still not comfortable, vaginal dilators may help. They can increase both the vaginal opening and the depth by gradually and gently stretching the tissue.
Keep working at it! Regaining your sex life is definitely worth some time and experimenting.